1. Field of the Invention (Technical Field)
The present invention relates to cleaning methods and apparatus, particularly methods for cleaning the interior of a container, and more specifically to an ultrasonic apparatus and method for removing energetic materials from explosive munitions intended for demilitarization.
2. Background Art
Changing military needs have resulted in changes to the types and quantities of conventional explosive munitions stored by the United States of America and other nations. More significantly, large quantities of munitions previously retained in military stockpiles currently are nearing the end of their useful or reliable lives. Accordingly, there is a rising demand for rapid, safe, and cost-effective methods for removing the energetic substances from within the casings of aged or obsolete ordnance.
The autoclave approach is the principal method currently employed for demilitarizing munitions. Simply described, the autoclave method involves the heating of the munitions to melt the energetic material. Typically, a munitions casing is held in an inverted position (i.e., with a casing opening disposed downward) and subjected to one or more jets of hot steam to heat the casing (and its contents) above the melting point of the energetic material. As the contained energetic material is heated above its melting point, it undergoes a phase shift from solid or semi-solid to liquid, and the melted material is permitted to flow from the casing into a suitable disposal container or system.
Though commonly employed, the autoclave method for demilitarizing explosive ordnance suffers from several drawbacks. The method cannot be used at all to remove energetic materials having high melting points. The method is energy intensive, requiring as it does the heating of large quantities of water to generate hot steam. Also, the autoclave method is quite slow; the cycle time to heat, drain, and cool a single ammunition item is substantial, thereby decreasing efficiency and increasing overall processing costs. Most importantly, the autoclave method generates significant volumes of toxic vapors that must be controlled; workers employing the method must be safeguarded against exposure to the emitted vapors.
Aging stockpiles around the world are giving rise to an increasing need for a safe and efficient mode of demilitarizing munitions. The present invention meets this rising but unmet need.